At least two of the young athletes who lit the Olympic cauldron at the end of Friday night's opening ceremony had been sworn to such secrecy that they did not even tell their parents about their role in Danny Boyle's extravaganza.

The identity of the final lighter of the Olympic flame had been the subject of frenzied speculation in the runup to the ceremony, and bookmakers took thousands of bets on who would have the honour.

But even the families of 18-year-olds Aidan Reynolds and Jordan Duckitt were kept in the dark as the nominees of some of Britain's most famous Olympians practised for the big moment, it has emerged.

"It was more just 'let's not talk to anybody'. We've just had cover stories," Duckitt told BBC Radio Lincolnshire. "The easiest thing was not being able to talk to anybody. Otherwise I would've let something slip."

Duckitt said he got the call asking him to be part of the finale last Thursday, eight days before the opening ceremony. He had been due to go on holiday with his parents, he said, but had to cancel everything. In blissful ignorance of his starring role, the family went away anyway.

"I'm flying out to see them tomorrow," said Duckitt, who was chairman of the London 2012 young ambassador steering group for two years and was nominated by Duncan Goodhew. A tweet he posted hours before the ceremony urged people to "#savethesurprise" for what he called "the greatest show on Earth".

Reynolds, a budding javelin star and the personal pick of the former Team GB captain Lynn Davies, also kept his role from his family. His mother, Teresa Reynolds, from Powys but living in Telford, Shropshire, told the BBC she had screamed at the television when she realised – but Aidan's grandparents had gone to bed thinking they had missed him.

"When he first got the phone call to ring his coach about the Olympics we thought it was a spoof," she said. "Then he went down to London and it was like he'd signed the Official Secrets Act almost, as he was not allowed to tell us anything, but he said it would be a surprise. We never dreamed he would be lighting the cauldron, though. We thought he would be one of the angels on the bikes."

Bookmakers including William Hill and Sky Bet said they would be refunding money placed on people thought to be likely cauldron lighters because the result had been so unpredictable.

The torchbearers lit some of the 206 petals, representing each competing nation, which spread to all the others. The petals then came together to make a single flame.

The cauldron team

Callum Airlie, 17 (nominated by Shirley Robertson)

Airlie had already carried the Olympic flame through his home town of Gordon, in Berwickshire, and hopes to compete in the 2016 Olympics in Rio de Janeiro. He has been sailing since the age of four and is a two-time Optimist UK national champion. His current target is to win the International Sailing Association and Federation Open Championships in 2013.

Jordan Duckitt, 18 (nominated by Duncan Goodhew)

Duckitt, from Caistor, Lincolnshire, was chairman of the London 2012 young ambassador steering group for two years and hopes to read medicine at the University of Edinburgh.

Desiree Henry, 16 (nominated by Daley Thompson)

In 2011, aged 15, Henry was the youngest member of the Great Britain youth team to gain a world 200m title at the IAAF world youth championships. She is the member of Enfield and Haringey athletics club and will compete in the world junior championships in Barcelona later this year.

Katie Kirk, 18 (nominated by Dame Mary Peters)

In 2010, at the age of 16, Kirk was selected to run at the Commonwealth Games in Delhi, India, in the 400m and 4x400m relay. A year later she was part of a gold-medal-winning team in the 4x400m relay at the European junior championships in Tallinn, Estonia. Kirk, from Holywood, County Down, is trained by her father, Mark Kirk, who represented Britain in the 800m.

Cameron MacRitchie, 19 (nominated by Sir Steve Redgrave)

At the 2012 GB rowing team under-23 trials in April, MacRitchie finished fifth with his partner James Edwards in the men's pair and was selected in the men's eight to race at the world rowing under-23 championships in Lithuania in July.

Aidan Reynolds, 18 (nominated by Lynn Davies)

Reynolds gave up a promising basketball career to focus on the javelin, winning three silver medals at national level at the English schools, UK school games and English championships.

Adelle Tracey, 19 (nominated by Dame Kelly Holmes)

Tracey, from Godalming, Surrey, has collected county, regional and national junior and senior titles in 400m and 800m, and has been in the top five of the UK rankings for six years. She won 800m silver for Great Britain in the European youth Olympic festival in Tampere, Finland. Tracey's dream, inspired by Holmes, is to compete in the Olympic Games. She is studying at the Arts University College in Bournemouth.